<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .active {
            color: red;
        }
    </style>
</head>

<body>
    <div id="app">
        <ul>
            <li v-for="(imet,index) in mouise" @click="ann(index)" :class="{active:index==indd}">{{index}}--{{imet}}</li>
        </ul>
    </div>
    <script src="../../node_modules/vue/dist/vue.js"></script>
    <script>
        var app = new Vue({
            el: '#app',
            data: {
                mouise: ['1', '2', '3', '4'],
                indd: 0

            },
            methods: {
                ann: function(index) {
                    this.indd = index;

                }
            }
        })
    </script>
</body>

</html>